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US 4,286,147 AGranted
In-focus detecting device
AssigneeUniversal Pioneer Corporation
InventorsHiroaki Tsuboi, Toshihiko Hosaka
Life of this patent
Estimating the term…
Abstract
A focus lens protecting and in-focus detecting device has light receiving circuit and a comparator for comparing the output of said light receiving elements with a reference potential. A switch network is controlled by the output of the comparator to supply signals to a focus control amplifier from the light receiving circuit.
Claims14
An in-foucs detecting device for a lens of an optical video disk player comprising;
- light quantity detecting means, comparator means for comparing the output of said light quantity detecting means with a reference voltage;
- switch means controlled by the output of said comparator means, and means for preventing said lens from contacting a disk being played on said video disk player.
A focus lens protecting device for use in an optical video disk player comprising:
- light quantity detecting means;
- comparator means for comparing the output of said light quantity detecting means with a reference potential;
- switch means controlled by the output of said comparator means;
- a focus control amplifier operable to drive said lens toward or away from a disk being played on said video disk player;
- and means receiving the output of said switch means for applying the output of said light quantity detecting means to the input of said focus control amplifier.
2 more elements
Dependencies are inferred from the claim text.